Electrophotographic image forming apparatuses, such as facsimile machines or printers, typically include a toner container for containing toner supplied to an image forming unit or waste toner (used toner) collected from the image forming unit. There are various types of toner containers different in shape. For example, cylindrical toner containers provided with a handle are proposed for ease of handling of the toner container.
In toner containers for supplied toner, typically an opening (toner outlet) connected to a toner inlet of a toner supply device is provided on a side face of a container body, while, in toner containers for waste toner, an opening (toner inlet) through which waste toner flows in is provided on a side face of a container body. Such openings are often disposed in an end portion of the container body on either the back side (distal side) or front side (proximal) of toner container is on the front side of the apparatus.
For example, an insertion opening for replacement of the toner container is formed in the front plate of the housing of the image forming apparatus. To remove the toner container from the apparatus, users can grip the handle of the toner container with one hand and pull out the toner container through the insertion opening, while supporting the container body with the other hand. Then, the toner container is placed horizontally on the floor or nearby table temporarily. To insert a new toner container into the apparatus body, users can grip the handle of the toner container with one hand and supports the container body with the other hand. Then, the removed toner container is collected in a collecting box or the like. It is to be noted that, toner containers for supplied toner are generally designed to be placed horizontally with the opening thereof faced up, and projections serving as legs are formed on a side face of the toner container opposite the opening (toner supply device).
Although the frequency of replacement of toner containers generally depends on the number of output sheets on which images have been formed, consumption of toner per sheet dramatically increases in the case of so-called solid images such as photographs whose printing ratio is high. Accordingly, replacement frequency of toner containers is high particularly in image forming apparatuses for forming a large amount of solid image, such as for use in the field of production printing. The increase in replacement frequency of toner containers is high can result in increases in the possibility that users or service persons place the toner container temporarily on the top face of the image forming apparatus or place the toner container vertically and directly on the nearby floor. The opening, namely, toner inlet or outlet, formed in (the toner supply device of) the toner container is generally opened or closed with a valve disc, and there may be some toner remaining adjacent to the opening. In case that the toner container placed vertically falls unexpectedly, the toner remaining adjacent to the opening might leak and scatter on the floor. Moreover, the fallen toner container can be damaged.
In view of the foregoing, for example, JP-2009-294406-A proposes providing a projection on a face of the toner container that is on the bottom when the toner container is placed vertically, thereby preventing the toner container from being placed vertically.
It, however, is still possible that the toner container falls with the opening faced down if the toner container is put on an unexpected plane, such as, an uneven surface. Referring to FIG. 1, when a toner container T having a projection P on a bottom face thereof in FIG. 1 is placed vertically on a stepped surface S, the projection P does not hinder the user from placing the toner container T vertically. If the user touches the toner container T carelessly, the toner container T might fall, causing scattering of toner from an opening M. Additionally, when the toner container T is placed on a thick carpet C, the projection P can sink in the carpet C, thus failing to prevent the user from placing the toner container T vertically.